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Installing Dusk to Dawn Photocell in Exterior Lighting to Save Power
By sblackb • Apr 12th, 2008 • Category: Energy Savings, Features
Project: Add photocell (dawn to dusk switch) to existing outdoor fixture.
Difficulty: Easy
Time: 30 minutes
Benefits: Eco Friendly, power saver, time saver, esthetically appealing
Cost: $5 – 10 depending on you collection of tools.
Today’s Watthack covers adding a photo cell to a patio light. This light is on our front porch and we typically turn it on when we get home, and turn it off in the morning. That’s just our routine so we don’t forget, but this wastes power as the days get longer. While visiting my big box home center, I picked up a photocell that will mount into the light fixture we have. It’s made as a replacement for Hampton Bay lights with photocells installed, but it’s simple enough to wire into just about any light. And, with a price of 5 – 6 dollars, it’s about half the price of other thread-in photocells.
For this project you will need:
- Access to the breakers so you can shut the circuit off
- A phillips and flat screwdriver
- 1 small wire nut
- 1 photocell
- A drill bit in the size that’s specified for the photocell you choose
- A drill of some sort.
- You may also want to have wire strippers handy.
- Utility knife
Let’s get started
First let me start off by saying that I’ve tried a few of the screw-in photocells. They are typically more expensive ($10 – $12,) don’t last as long, and generally look like crap when installed in any light with a clear glass globe like ours. Thread in photocells are easy to install, but we get to use power tools with this version; a definite bonus.
The project starts by disconnecting power to the lighting circuit. If it’s a switched circuit, you could just turn off the switch, but if anyone else is home, you are asking for shock treatment. Be safe and take the time to kill power to the whole circuit.
Next, we remove the light fixture by unscrewing the two retaining nuts on either side of the light base. Your fixture will vary, so take your time and locate the hardware you need to remove. Also, if your trusty painter caulked and painted around the light fixture, you may want 
to locate a utility knife and score the paint between the wall and fixture. This will prevent you from needing to repaint.
Our house was built in 1938, so our wiring is pretty simple. One neutral (white) wire, and one power or hot wire (black.) You may have another wire that is either copper or green which is considered the Ground wire. Disconnect all the wires and pull the fight fixture down. You should have matching colors on your light fixture. If not, take a minute to label each wire so you remember how it goes back together.
Remove any glass that might fall out or get broken while you drill your hole. Also take a look inside your housing and at any bracket that is attached to the electrical box to determine the best location for the photocell on the base of the light. I decided mine would look and perform best if the photocell was at the bottom of the base pointing down. This turned out to be a big mistake. As it would turn out, I didn’t account for the output of the light itself, so the brighter the light got, the more the photocell would try to shut it off. The result was a dimly flickering bulb that was far from useful. To correct this, I will need to move the photocell into an area that is shaded from the light.
I happen to have a drill press in the woodshop, so that’s where I headed to make my hole. However, a handheld drill will work just as well.
Double check you drill bit size – you only get one shot at this, so don’t make your hole too big. After all, the beauty of this photocell project is that it will be hardly noticeable once complete.
You may want to have some blocking to help keep the fixture level while you drill. Start drilling and take your time. The harder you press the hotter the bit gets and you risk denting your fixture. Spray a little WD-40 on the bit or use cutting oil if you have it.
Once your hole is drilled, be careful to not cut yourself on the sharp edge. I used a small file to knock down some of the sharp edges. This step is not necessary since the edge will not be exposed once the photocell is installed – just be careful.
Remove the retaining nut from the photocell and uncoil the wires. This will be a lot easier and safer before the photocell is secured in place. From the inside of the light, slide the threaded shaft of the photocell through the hole you just made and thread the retailing nut back on. If your photocell has adjustments or wiring diagrams on its housing, be sure that this is facing out so they are accessible.
Pay attention to the wiring instructions on the packaging or the body of the photocell. Ours indicated that one of the black wires should be connected to the light, and the other to the black wire coming from the wall. So power would run from the house, into the photocell, then into the light. The photocell acts as a secondary switch that opens and closes depending on the amount of light. One nice feature of the photocell that I purchased is that is actually dims – that is, the more light outside, the lower the light output. Conversely, the darker it is outside, the brighter the light output. Pretty cool!
Connect the black wires based on the directions that came with your photo cell.
Connect the white wires together making sure to tuck them back into the electrical box.
Connect the green/copper wires together making sure to tuck them back into the electrical box.
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Replace or tighten any mounting brackets that you removed or loosened to remove the light fixture.
Install retaining nuts that hold the fixture to the electrical box.
Turn your breaker back on and wait for dark. Really, that’s all there is too it. If you are like me and can’t wait, you can block off light to the photocell to see the light turn on.
This was a simple and inexpensive project that anyone with the right tools can do. Not only is it more convenient because we don’t need to remember to turn it on, it save power each day by matching its output with the sun’s. I have a hunch I will be adding a few more of these around the house. If you want to purchase the photocell that I’m
using, the sku is 594-135 and can be located in the lighting section of Home Depot. I hope you found this guide useful and are now contemplating adding photocells of your own.
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sblackb is Scott and Liz share a passion for the outdoors and want to help protect the natural beauty of our planet. Scott feels like one of the best ways to accomplish this is to take on responsible power use, generation and learning new methods for better living with less resources.
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Should there be 2 photocells on 2 different lights that operate on the same circuit?
I bought a timer that replaces the light switch , that operates three outside light fixtures.All three lights have cfl's. the fixtures came originaly with photocells,so when the photocells stopped working I put the timer in.The cfl's would not work with the photocell but it loves the timer and so do I.I set it once over two years ago. and have not changed a lamp since.The timer cost about thirty bucks at lowes,. You must disconnect the photocell if it is still working in the fixture.
Cap, check out the follow-up article I did on alternatives to the Hampton Bay Photo Cell.
http://www.watthackers.com/wp/more-options-for-in...
Hey this was fun to read. I did exactly what you did with our front porch lights back in 06 when we built the house using the exact Hampton Bay replacement photocell and drilling the hold twice because I too put it on the bottom and had the flickering light thing. By moving it to the topiIt worked great for about 2 years then the photocell went out. I installed another one and it lasted exactly 2 more years and now nada. I have to do it again. Luckily it's not hard just a pain in the neck and irritating they can't make something last longer than that. Is there a higher quality replacement photo cell out there? I'd rather pay $25 and have it work than to keep replacing the shoddy hampton bay part.
I just installed photocells on my outdoor lights and discovered some things that might be good to know. I found the same photocell as the one shown here at Home Depot for about $7.50. The packaging was updated a bit and it now says that they are not compatible with compact fluorescent bulbs. Since that’s all I use, I kept shopping. I eventually found a photocell sold at Ace Hardware (AA-105-BPA) for the same price.
The advantages of the Ace Hardware photocell are it works with all types of bulbs up to 1800 watts and it has a built-in timer to delay the on/off switching and help eliminate any flicker. (Of course, it still has to be mounted where the light doesn’t shine on it.) The disadvantages are it has a little bigger housing, which might limit where it will fit and it doesn’t include a backing nut, which is required if you want the photocell to protrude out of your fixture as little as possible. These nuts are virtually impossible to buy separately, but I was able to get the same result using some 5/8″ rubber grommets as spacers.
Another useful tip I discovered when installing my photocells is if one switch controls multiple outdoor lights, those lights are often wired in series. In that case, a photocell can be installed on just the first fixture (closest to the wall switch) and the wires can be connected so that photocell will also control all the other lights after it. Basically, you separate the three black wires behind the first fixture, connect the black wire that runs to the wall switch to the black wire on the photocell. Next, connect the black wire from the light fixture, along with the black wire that runs to the other lights to the red wire on the photocell. Connect all the white wires together as normal.
I can now finally leave my outside light switch on and the photocells take care of the rest. Now if I can just figure out how to keep all the bugs from building nests inside my nice warm fixtures.
Thanks for posting this project, I just installed this photo sensor on 2 exterior LED latterns, WORKS GREAT!!! My Home Depot had these sensors for $7 each. cheers!
[...] no timer needed. Turns on at dusk and off at dawn. You can get these at Lowe’s, Home Depot. http://www.watthackers.com/wp/instal…to-save-power/ [+] Rate this post [...]
[...] Installing Dusk to Dawn Photocell in Exterior Lighting to Save Posted by root 3 hours ago (http://www.watthackers.com) I would like to install a hampton bay photocell switch sku 594 135 to control a cluster of 110v light i finally decided to write a comment on your blog Discuss | Bury | News | Installing Dusk to Dawn Photocell in Exterior Lighting to Save [...]
I can not find the photoswitch with the info provided….
[...] By sblackb • Dec 1st, 2008 • Category: Energy Savings When I wrote the article on installing a dusk to dawn photo cell to control exterior lighting, I had no idea that is would be such a popular project. Not only from the feedback that I have [...]
Interesting reading here and on BobVila.com concerning the Hampton Bay SKU#594-135 photo cells. I had 2 old fixtures with photo cells that operated prefectly with a single pair of CFLs for 3 years. As part of a renovation, I installed new fixtures with Hampton Bay photo cells. The new fixtures killed thoses old CFLs in less than 1 week. Also killed 2 new CFLs, 1 dimmable CFL and 2 incandescent bulbs before I removed them from the fixtures.
That’s a lot of light bulbs over just 1 month of operation – now I just have CFLs on 24/7. So much for saving the Planet (and my $$).
Yes, the cells were properly installed so that they were shaded and did not see the light from the fixture or any other nearby lights – they were aimed into open space. Does anybody know of any small/thin photo sensors available anywhere?
about the photocell wiring….what if i have two black wires and two white wires and two grounds coming out of the electrical box????? thank you, respectfully, sharon
I would like to install a Hampton Bay photocell switch SKU 594-135 to control a cluster of 110V light bulbs, but do not know the maximum wattage rating of the device. Please provide this info. Thank you.
Dean,
Sorry to hear that you had the same problem I did with locating the sensor. Now that I moved mine however, it has been going strong ever since. As for bulbs, I’m currently using an incandescent bulb simply because I had one on hand. Since the photocell functions like a dimmer (slowly turning the light on and off at dawn and dusk,) you would need to get a fluorescent bulb that is dimmable and those are still pretty expensive.
I would not suggest halogen due to the extra power they draw. Stick to a low wattage incandescent bulb and see how your sensor works. Remember you are saving a ton of power just by having the light turn on and off as the sun sets and rises. When it burns out in the future, check the prices of dimmable CFLs.
Hope that helps. Thanks for being a Watthacker.
Scott
OK, thank you. I will try to relocate the sensor. My other question is what bulb should go there? Reg incandescent or fluorescent or halogen?
Richard,
I discovered the sensor on one of my many unrelated trips to HD, but I couldn’t locate it on their website either. If you are near a HD, you can find them stocked back by the outdoor lighting fixture section. There was only one photocell to choose from. A word of caution – After googling for an alternative sensor, I discovered several reports of faulty photocells from Hampton Bay. They eventually short and take the bulb out. Once you replace the bulb, the sensor no longer functions as designed. I guess we will see how long ours lasts. I will look for alternatives and post them here.
This photo cell is just the item I’ve been looking for. I went to HOME DEPOT lighting section and entered the sku # 594-135, but it came up “sorry no matches found”. Would you have any other suggestions as to where I can obtain the photo cell. Thanks
Dean,
You may have made the same mistake I did at first. You need to make sure the photocell is shaded from the light being produced by light fixture. Otherwise, their will be a constant battle between the light and the photocell. Try blocking the sensor with your hand. If the light turns on and stops flickering, placement is the problem. The sensor that I used was for a 120 volt application. Hope that helps.
Scott
I installed this wire-in control on a porch resessed can. I can not get any buld to work correctly. most will filcker intently. is ther a specail lamp that needs to be used? i read on another page that this is a replacement switch and needs to be used on a 12V lamp. my lamp is a 110V,
thanks
Dean
I finally decided to write a comment on your blog. I just wanted to say good job. I really enjoy reading your posts.
Tina Russell